222
FXUS63 KDTX 172256
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
656 PM EDT Wed Jul 17 2024

.KEY MESSAGES...

* An upper level disturbance will cross through Lower Michigan
  this afternoon and produce scattered showers and thunderstorms
  into early this evening.

* High pressure brings cooler, drier, and less humid conditions
  to the region through the end of the workweek.

* Temperatures moderate over the weekend as high pressure departs,
  followed by an approaching boundary Sunday which offers low-end
  precipitation chances.

&&

.AVIATION...

Sfc observations show much drier air now infiltrating Se Mi from the
northwest. This is quickly stabilizing the airmass across Se Mi. The
areas of convection across northern Michigan is a result of the mid
level cold pool associated with an upper trough. This cold pool aloft
will drift across Lake Huron this evening, keeping any residual
showers/thunderstorms focused mainly over Lake Huron. The northern
gradient during the night in advance of sfc high pressure expanding
in from the west will maintain a light NNW wind through the night.

For DTW/D21 Convection...No convection is expected through the TAF
period.

DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 259 PM EDT Wed Jul 17 2024

DISCUSSION...

Passing mid level upper trough axis and associated mid level cold
pool will support isolated to scattered convection this afternoon
into early this evening as it sweeps east through the forecast area.
The most robust activity will impact areas just north of the region,
but some degree of a southern expansion is expected along the trough
this afternoon. With H5 temperatures to -15C or below (helping to
generate SBCAPES of 500-1000 J/kg during peak afternoon heating), a
few stronger updrafts will likely produce isolated small hail. This
activity will be most pronounced in the 2-5 pm time frame with any
lingering activity early this evening dissipating and it progresses
east out of lower MI.

Cool conditions for mid July can be expected as this upper trough
digs through the area with minimum temperatures in the lower/mid 50s
late tonight and again Thursday night. Meanwhile, high temperatures
on Thursday will hold in the low/mid 70s. The Canadian high pressure
responsible for the cooler conditions will moderate into the weekend
with temperatures building back into the lower 80s in most cases
(but with relatively low humidity levels). Even as the high pressure
does weaken in time, generally dry weather will persist into Sunday
with perhaps an isolated late day shower possible by that time.

Similar temperatures in the upper 70s to lower 80s will persist into
early next week as main upper level ridging remains positioned well
off to the west mainly from the high plains into the Rocky Mountains
on to the west coast. Some minor shower chances look to re-establish
in this later portion of the forecast. That said, confidence is very
low in details as no particularly impressive synoptic scale systems
are slated into the area. At most, it appears a weak mid level wave
that cuts off over the central plains/midwest this weekend may be
pulled east into the area in advance of another decent shortwave
dropping southeast through eastern Canada into the Great Lakes and
northeast CONUS.

MARINE...

Once scattered showers and isolated thunderstorms clear this
afternoon, cooler and drier air settles into the Central Great Lakes
through tomorrow, as a large Canadian high pressure buids over the
region. This expansive high will provide dry and benign marine
conditions right through the Weekend and into early next week.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

AVIATION.....SC
DISCUSSION...DG
MARINE.......sf


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